drm/i915/vlv: check port in infoframe_enabled v2

Same as IBX and G4x, they all share the same genetic material.

v2: we all need a bit more port in our lives

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>